Embodiments of the present invention relate to a medical device. More specifically, embodiments of the present invention relate to a catheter.
A catheter is a medical device that is inserted into a body cavity, such as an abdominal cavity or a lumen, such as a ureter or a blood vessel, to inject a medicine into a lesion or to drain a bodily fluid.
A balloon catheter is a type of catheter used for percutaneous transluminal coronary angioplasty. Guided by a guidewire that has been inserted into a blood vessel, a balloon catheter can reach a stenosed or obstructed lesion and can restore normal blood flow by dilating the lesion with a balloon.
In general, a balloon catheter includes a proximal shaft that is positioned near an operator, a distal shaft that is joined to the proximal shaft and positioned near a lesion, an inflatable and deflatable balloon that is formed in a distal end portion of the distal shaft, and an inner shaft that is disposed in the inner cavity of the distal shaft and extends through the inner cavity of the balloon (see, for example, Japanese Unexamined Patent Application Publication No. 2003-164528).
A space is formed between the distal shaft and the inner shaft, which is disposed in the inner cavity of the distal shaft. The inner cavity of the proximal shaft, the inner cavity of distal shaft, and the inner cavity of the balloon are connected to each other. Therefore, a liquid, such as a contrast medium or a physiological saline, can be supplied to the inner cavity of the balloon through the inner cavities of the proximal shaft and the distal shaft, and thereby the balloon can be inflated and deflated at will.
The inner shaft has another inner cavity that is isolated from the inner cavities of the proximal shaft, the distal shaft, and the balloon. The catheter can be guided to a lesion by inserting a guidewire through the inner cavity of the inner shaft.
Referring to FIGS. 4A to 4C, the structure of a Related Art balloon catheter described in Japanese Unexamined Patent Application Publication No. 2003-164528 will be described below.
FIG. 4A is a partially enlarged plan view of the Related Art balloon catheter, illustrating a joint portion between a core wire and a proximal shaft, FIG. 4B is a partially enlarged side view of the joint portion of FIG. 4A, and FIG. 4C is a partially enlarged side view of the joint portion of FIG. 4B when a bending force is applied to the joint portion. In FIGS. 4A to 4C, the left side is the distal side, and the right side is the proximal side.
As illustrated in FIGS. 4A and 4B, a distal end portion 421 of a proximal shaft 420 is fitted into the inner cavity of a proximal end portion of a distal shaft 430. A core wire 440 extends through the inner cavities of the distal shaft 430 and the distal end portion 421 of the proximal shaft 420. The proximal end of the core wire 440 is joined to the inner surface of the distal end portion 421 of the proximal shaft 420 through joining means 450 such as a weld.
It is described in Japanese Unexamined Patent Application Publication No. 2003-164528 that, in the Related Art balloon catheter 400, the distal end portion 421 of the proximal shaft 420, which is fitted into the inner cavity of the proximal end portion of the distal shaft 430, is inclined toward the distal end, and thereby change in the rigidity of the Related Art balloon catheter at the boundary between the proximal shaft 420 and the distal shaft 430 can be reduced.